1. Field of the Invention
The present invention relates generally to the field of implanting of inert or active medical devices for remedial benefit or for extended release of various drugs. More particularly, the present invention provides a self-contained disposable cartridge having an integral penetration tip which is frangible subsequent to insertion for implanting of a medicament or device maintained in a sterile environment within the sealed cartridge prior to insertion.
2. Description of the Prior Art
Application of medicaments to patients over an extended period of time has become possible with the use of timed release implants (TRI) which are inserted subcutaneously in the patient and provide release of the medicament included in the implant over a significant period of time. Use of TRIs in the contraceptive field and for administration of insulin and other drugs for control of diabetes are becoming conventionally accepted means for medication of patients. Modern genetic engineering is increasingly leading to cures of a variety of diseases by replacement of missing body chemistry. The TRI provides a convenient, medically efficient and cost-effective method of introducing such drugs to a patient.
TRIs and similar devices are currently implanted surgically or using insertion devices having large-bore needles through which the encapsulated implant is inserted. Such devices typically require high-cost sterilizable components due to the size of the implants themselves. Use of a large-bore needle of the type necessary to pass an implant device can cause serious trauma through coring where the hollow needle actually cuts out a plug of tissue when inserted. In order to prevent coring, the use of a stylette or other means to block the needle bore during insertion is required which adds to the complexity of the insertion device, its associated cost and sterilization requirements. Additionally, a determination of the depth of insertion for the implant site and accurate placement of the implant are required. Conventional beveled needles, particularly of large bore, have a tendency to slice through tissue at an angle to the needle axis, thereby making control of needle insertion and consequent accuracy of placement of the implant device, difficult. Alternatively, placement of implant devices is accomplished at surgically accessed sites by manipulation with forceps or other common surgical tools. These procedures take considerable time to perform, result in greater trauma to the patient and require extreme care in avoiding contamination of the implant device during extraction from packaging and handling.
A determination of the depth of the implant typically requires a special gauge, or is measured by approximating the depth of insertion through measurement of the exposed portion of the needle. Either process is typically time-consuming and subject to error or accidental contamination of the implantation site.
It is therefore desirable that an implant insertion device comprise a disposable portion which maintains the implant in a sterile environment and is itself easy to maintain in a sterile condition prior to use. It is further desirable that the implant device include a symmetrical non-coring piercing device with integrated insertion depth measurement to allow accurate insertion of an implant through an existing orifice, subdurally, subcutaneously or in an intramuscular location as appropriate for the particular implant or device.